Short days and long periods of darkness,or dim light, mark the season of winter. North of the equator, the season spans December through February, while south of the equator it encompasses June through August. Plants in winter not only contend with the decrease in light but also low temperatures and heightened but sometimes unavailable precipitation. Adapting to this season allows flora to survive this period.
Green plants rely on sunlight for conducting photosynthesis, which allows them to make food. Winter greatly curtails the available sunlight. Cold temperatures stop plant growth. For commercial plant growers, winter presents a two-fold challenge. There is the danger of losing annual stock to early cold snaps, while some plants must stay alive no less than one winter before being eligible for sale. The latter need winter acclimation.
Annual plants die at the end of summer and during fall. These species survive the winter in the form of seeds that sprout again when spring arrives and higher temperatures warm the soil that may still be moist from the last snowfalls or winter rains. Examples of annuals include the Common Snapdragon (Antirrhinum majus), the California Poppy (Eschscholzia californica), and the Primrose (Primula vulgaris).
Perennial Geophytes Features
Geophytes are perennial plants with tubers, bulbs, rhizomes or corms as part of their root systems. Some geophytes with an underground storage organ die back above-ground after blooming and producing seeds, while going dormant below-ground. Examples include tulips and hyacinths. Other geophytes, notably Banana trees, rely on corms to survive adverse weather; this allows them to re-grow after being severely damaged above-ground by cold temperatures or high winds.
Danger to Evergreens
Evergreen plants face significant dangers during the winter months. Southern Japanese Hemlock (Tsuga sieboldii), rhododendrons and other evergreen plants in winter are subject to frost burn. Frost covers the leaves and when the sunlight shines on the frozen areas, a burn occurs and the leaves discolor. While this condition is not life threatening to the plants, the same cannot be said for wind burn. Cold wind causes moisture-loss to leaf-bearing evergreens. If the ground is frozen and prevents the uptake of water, the damage is deadly to the plants. Protecting evergreens with windbreaks or wrapping the plants with a protective layering of burlap can prevent extensive damage from wind burn.
Prepare perennial plants for winter by focusing on building up their health during the summer months with proper fertilizing. Anticipate the first frost and stop fertilizing the plants about six weeks ahead of that date. It is crucial to limit the available nitrate in the soil to halt new growth too close to winter. Supplement potassium, since this substance assists plants with maintaining the porous quality of cell membranes, which later protect against cellular freeze damage during the coldest temperatures. Applying mulch to planting beds helps protect against extreme freezing and thawing of the soil.